1. Field
The present invention relates to a driving circuit and a driving method for a plasma display panel (PDP), and more particularly to a driving circuit and a driving method capable of reducing the generation of sudden large current in a reset period of scan driving signals.
2. Description of the Related Technology
A plasma display panel (hereinafter, referred to as a ‘PDP’) displays an image by light-emitting phosphors excited with ultraviolet light generated during the discharge of an inert mixed gas such as He+Xe, Ne+Xe, He+Ne+Xe, etc. This PDP can be easily made thin and large, and it can provide greatly increased image quality with the recent development of the relevant technology.
Referring to FIG. 1, the discharge cell of a three-electrode AC surface discharge type PDP includes scan electrodes Y1 to Yn, a sustain electrode X, and address electrodes A1 to Am perpendicular to the scan electrodes Y1 to Yn and the sustain electrode X.
A cell 1 for displaying any one of red, green, and blue is formed near an intersection of the scan electrodes Y1 to Yn, the sustain electrode X, and the address electrodes A1 to Am. The scan electrodes Y1 to Yn and the sustain electrode X are formed on an upper substrate, which is not shown.
A dielectric layer and MgO protective layer, which are not shown, are formed on the upper substrate. The address electrodes A1 to Am are formed on a lower substrate, which is not shown. Barrier ribs for preventing optical and electrical radio interference between horizontally neighboring discharge cells are formed on the lower substrate. A phosphor layer configured to be excited with an vacuum ultraviolet light to emit a visible light is formed on the substrate and the surface of the barrier ribs. An inert mixed gas such as He+Xe, Ne+Xe, He+Ne+Xe, etc. is injected into the discharge space between the upper substrate and the lower substrate.
The PDP is driven with one frame being divided into several sub-fields having a different amount of emission in order to implement the gray scale of an image. Each of the sub-fields is divided into a reset period for initializing the whole screen, an address period for selecting a scan line and selecting a cell in the selected scan line to emit light, and a sustain period for implementing the gray scale according to the data. For example, if it is desired to display an image with 256 gray scales, a frame period (16.67 ms) corresponding to 1/60 second is divided into eight sub-fields SF1 to SF8, as shown in FIG. 2. Each of the sub-fields SF1 to SF8 is subdivided into a reset period, an address period, and a sustain period, as described above. The reset period and the address period of each of the sub-fields are overlapping in every sub-field, whereas the sustain period and the number of sustain pulses allocated thereto increase in the ratio of 2n (where, n=0,1,2,3,4,5,6,7) in each sub-field.
The driving waveform of the PDP supplied to each sub-field is driven by being divided into a reset period for initializing whole screens, a address period for selecting a cell, and a sustain period for maintaining the discharge of the selected cell. The reset period generally generates a rising ramp waveform in a positive direction having large peak value, wherein there is a sudden flow of large current according to the rising ramp waveform. The sudden flow of large current lowers the discharge efficiency of the PDP and deteriorates driving quality.
In order to prevent the sudden flow of large current in the reset period, the Y electrodes are divided into two groups to be driven with the difference between a rising time point and a falling time point of the scan driving signals applied to each group in the reset period, making it possible to reduce the flow of current by half. However, regarding the generation of different scan driving signals in every group of the Y electrodes, the implementation thereof is not as easy and the burden in view of hardware is large so that the application to group the Y electrodes into more than two has not been widely used.
Also, regarding the generation of different scan driving signals in every group of the Y electrodes, as the size of a panel becomes large, the driving circuit part thereof should be greatly changed, resulting in that it may increase manufacturing costs.